1. Field of the Invention
The present invention relates to a data recording and reproducing apparatus having reduced power consumption.
2. Description of the Related Art
In recent years, the number of battery-driven apparatuses such as personal computers has greatly increased, and the demand for reduced power consumption by the magnetic disk drive incorporated in the apparatuses has also increased. The factors determining power consumption by the magnetic disk drive are: the drive current of the spindle motor and the drive current of the voice coil motor. The spindle motor is used to rotate the recording medium, such as a magnetic disk, and is comprised, for example, by a brushless DC motor. The voice coil motor is used to move the magnetic head of the magnetic disk drive in the radial direction of the recording medium.
The spindle motor is controlled such that it rotates at a constant speed when the magnetic disk drive is operated. The voice coil motor is driven only when the magnetic head is moved to a destination track of the recording medium. Hence, when the magnetic head is moved, both the spindle motor and the voice coil motor being simultaneously driven, the magnetic disk drive consumes the most power. As a result, when the magnetic disk drive is incorporated in an apparatus (for example, battery-driven personal computer or word processor) which is particularly sensitive to power consumption demands a problem may arise.
Published Unexamined Japanese Patent Application No. 1-102770 discloses a method of reducing power consumption in a battery-driven apparatus. In this method, operation of the spindle motor is stopped during acceleration and deceleration periods for the magnetic head during seek operations, thereby saving power. The spindle motor is driven only while the magnetic head is in a constant state of velocity, and, thus, the problem of power consumption during acceleration/deceleration periods for the magnetic head is reduced.
In other words, the magnetic head is moved at a desired destination velocity during a constant velocity period. Therefore, a driving current is supplied to a voice coil motor to move the magnetic head at the desired destination velocity during the constant velocity period. However, the power consumed by the supplying drive current during the constant velocity period is not inconsequential. Hence, there remains an unmet demand for a data recording and reproducing apparatus having reduced power consumption.